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Re: pre-monoblock 101 [Re: John Healy] #778418 07/11/19 10:00 pm
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Originally Posted by John Healy
Rohan: It is in small writing easily overlooked at the bottom of the page.

It is also on a page that is not easily found by their search engine.


I think you have completely missed my point John,
given that I QUOTED that small text in a previous post !!

P.S. I don''t know how I posted something 3 times, now fixed.

PPS Why have we diverged into Monoblocs. ?
Fuel density could be the reason for those 3 notches, I'm not sure if replies are directed at this ??
Would alcohol fuel require a different float setting ?

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Re: pre-monoblock 101 [Re: Richrd] #778450 07/12/19 9:35 am
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Allan Gill Online Happy
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Gasoline should be around the sg of 0.71 to 0.76, distilled water would have an sg of 1.0 (or 0.9982 to be more precice at 15*c), white spirit, diesel, and many solvents will have an sg of around 0.80 (methanol is 0.972) Thus us if you set your float height up using water or solvent, and use the liquid level to set the seat height, then soon as you switch to the lower density gasoline the float will sit more into the fuel thus the fuel level will be higher in the bowl, although not by a massive amout between methanol and gasoline.


Last edited by Allan Gill; 07/12/19 10:18 pm.

beerchug
Re: pre-monoblock 101 [Re: Richrd] #778463 07/12/19 1:07 pm
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John Healy Offline
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Yes, I changed the post.


Re: pre-monoblock 101 [Re: John Healy] #778503 07/12/19 10:23 pm
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Allan Gill Online Happy
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Originally Posted by John Healy
Yes, I changed the post.


No worries, I was hoping that I'd over looked something. I've removed mine as it serves no purpose.


beerchug
Re: pre-monoblock 101 [Re: Richrd] #778531 07/13/19 6:11 am
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Rohan Offline
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Another float needle with multiple notches.
(and imperfect focus...)
Although obviously not the same as previous.
I'm starting to wonder if this is an undocumented feature, rather than homemade modifications ?

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Re: pre-monoblock 101 [Re: Richrd] #778686 07/15/19 3:17 am
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Rohan Offline
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Something else I see which can vary is the different heights of collars(arrowed) under the mixing chamber.
This would rather alter the fuel height inside.
Anyone know how/why this may be, I'd think the carb on the right would be impossible to operate as is.
Would a different form of float bowl be required ? or ....

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Re: pre-monoblock 101 [Re: Richrd] #778736 07/15/19 7:17 pm
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Richrd Offline OP
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thanks for all this info.

the reason for the original post is that we are working on a rapide with new carbs and some problems. It ran great with Concentrics.

but with the new carbs there is a big stubble at 1/2 to 3/4 throttle, right where you'd expect the mains to be kicking in. Paul tried raising the needles but that makes it worse across the board.

and one carb does like to leak out the bottom.


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Re: pre-monoblock 101 [Re: Richrd] #778738 07/15/19 8:09 pm
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That leak could be the problem. Or do you have the correct float bowls for the cylinder they are being fitted to?


beerchug
Re: pre-monoblock 101 [Re: Richrd] #778751 07/15/19 10:34 pm
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Originally Posted by Richrd
with the new carbs there is a big stubble at 1/2 to 3/4 throttle, right where you'd expect the mains to be kicking in. Paul tried raising the needles but that makes it worse across the board.

and one carb does like to leak out the bottom.
Based on too little information I'll go out on a limb and say your main jets are too large, causing the stumble because it is too rich, and raising the needle was the wrong thing to do since it only made it richer in the 1/2-3/4 range, which is before you'd expect the main jets to be kicking in. Along with this, either the float level of one carburetor is too high or, if the leak really is coming from the bottom and not just collecting there, the gasket at the bottom is leaking.

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